This invention relates generally to mechanisms for deadlocking door members to door frame members in such manner as to accommodate sudden opening of the door members as by sudden pushing of associated panic bars.
Safety exit doors are widely used, and they commonly incorporate lock mechanisms which lock the doors to door frames, and which are releasable by operation of panic bars. See U.S. Pat. Nos. 1,638,748; 4,130,306; 4,083,590; and 4,368,905.
There is need for simple, compact, reliable mechanisms of this type which are readily installable upon such doors and door frame members to thereby provide safety exit door operation. U.S. patent application Ser. No. 067,132, filed June 29, 1987, and entitled "Lock Mechanism for a Safety Exit Door" provides a mechanism of this type, wherein a latching part in the form of a drum is rotatable about a horizontal axis to captivate a bolt member that projects downwardly from a door frame member. One disadvantage of such a latching part in the form of a drum is the requirement for precise relative vertical spacing of the drum relative to the bolt, i.e. the lack of sufficient vertical spacing tolerance as between the drum and bolt. Such tolerance is very desirable to accommodate installation of the apparatus to doors of different types and which may tend to move vertically somewhat as they swing between open and closed positions.
Another latching mechanism of this class is shown in U.K. Patent No. 20 80391 entitled, "Exit Door Locking Mechanisms Having Multiple Bolts." One problem with that mechanism is the lack of full captivation of the bolt, i.e. on all sides, by the latching part.